A focal plane array is an array of light-sensing pixels at the focal plane of a lens. Focal plane arrays are commonly used for both imaging and non-imaging purposes, such as spectrometry, and civil and military sensing. Focal plane arrays operate by detecting photons at particular wavelengths and then generating an electrical charge, voltage, or resistance in relation to the number of photons detected at each pixel. This charge, voltage, or resistance is then measured, digitized, and used to construct an image of the object, scene, or phenomenon that emitted the photons.
Typically, focal plane arrays are two-dimensional devices that are sensitive in the infrared spectrum. Focal plane arrays can operate at other spectra, such as the visible spectrum. Examples of focal plane arrays sensitive in the visible spectrum include CCDs and CMOS image sensors.
As the size of devices using focal plane arrays decreases, focal plane arrays become smaller and more complex. A solution to reduce focal plane array complexity is to use curved focal plane arrays as opposed to planar focal plane arrays. One advantage of a curved focal plane array is its field curvature. Curved focal plane arrays previously reported have a radius of curvature ≧5 meters.